Automatic closure for containers

ABSTRACT

This invention is an improved automatic closure for squeeze bottles or the like tubes or containers of the type formed from semirigid, flexible material such as polyethylene or semirigid polyvinyl chloride having properties of resilient flexibility, and means and methods for making the same. The container is provided with a preferably tapered neck portion terminating in lips and edges forming an openable closure elongate in cross section. One or both of these lips is preferably formed with an inherent reentrant or inward curve or set so that when the tapered side edges are sealed together and the lips are pressed together they provide the closure, which is opened by pressure digitally exerted on the container and closes on release of pressure. A closure which can effectively seal is realized in this manner by way of a preferred sealing technique. In this technique, sealing dies are used having nonsealing inserts so that when sealing, the outlet of the container is subjected to a uniform clamping pressure so that the outlet thereof is held fully flattened and uniformly closed during the sealing operation, both in and adjacent the closure to obviate the formation of irregularities and leaks at and adjacent the sealed edges. Upon release of clamping pressure the preferred form of outlet retains an inherent closing bias. A tear-strip seals the outer end of the end of the closure until removed in a manner heretofore disclosed.

United States Patent [72] Inventor Albert M.I-Ierzig 9465 Wilshire Blvd., Beverly Hills, Calif. 90211 [21] Appl. No. 842,108 [22] Filed July 16, 1969 [45] Patented Oct. 5, 1971 [54] AUTOMATIC CLOSURE FOR CONTAINERS 4 Claims, 34 Drawing Figs.

[52] U.S.Cl 222/213, 222/494 [51] Int. Cl B65d1/32 [50] Field of Search 222/213,

[56] References Cited UNITED STATES PATENTS 1,592,584 7/1926 Viegelmann 222/491 X 1,738,080 12/1929 Smith 222/494 X 2,546,709 3/1951 Abarr 222/490 X 2,589,743 3/1952 Snaith 222/294 X 2,753,091 7/1956 Herzig 222/491 2,815,150 12/1957 Herzig 222/491 X 3,315,849 4/1967 l-lerzig 222/491 Primary ExaminerM. Henson Wood, Jr. Assistant Examiner-John J. Love AtmrneyHerzig & Walsh ABSTRACT: This invention is an improved automatic closure for squeeze bottles or the like tubes or containers of the type formed from semirigid, flexible material such as polyethylene or semirigid polyvinyl chloride having properties of resilient flexibility, and means and methods for making the same. The container is provided with a preferably tapered neck portion terminating in lips and edges forming an openable closure elongate in cross section. One or both of these lips is preferably formed with an inherent reentrant or inward curve or set so that when the tapered side edges are sealed together and the lips are pressed together they provide the closure, which is opened by pressure digitally exerted on the container and closes on release of pressure. A closure which can effectively seal is realized in this manner by way of a preferred sealing technique. In this technique, sealing dies are used having nonsealing inserts so that when sealing, the outlet of the container is subjected to a uniform clamping pressure so that the outlet thereof is held fully flattened and uniformly closed during the scaling operation, both in and adjacent the closure to obviate the formation of irregularities and leaks at and adjacent the sealed edges. Upon release of clamping pressure the preferred form of outlet retains an inherent closing bias. A tear-strip seals the outer end of the end of the closure until removed in a manner heretofore disclosed.

PATENTEDnm 5m 3.610477 sum 1 or 4 INVENTOR A567 M. #662/@ M muw AUTOMATIC CLOSURE FOR CONTAINERS BACKGROUND OF THE INVENTION The background of the invention with respect to the general type of automatic closure and tear strip is found in prior US. Pat. Nos. 2,753,091 and 2,815,150. Further background is present in U.S. Pat. Nos. 3,315,849 and in applications, Ser. No. 535,111, filed Mar. 17, 1966, now Pat. No. 3,451,120 and Ser. No. 774,842,1iled Nov. 12, 1968.

The herein invention provides an improved automatic closure for a container and an improved method and means of fabricating it. The closure is an improvement over that of US. Pat. Nos. 2,753,091; 2,815,150; and 3,315,849, and that of the applications referred to. The method of fabricating is an improvement over the methods described in the previous patents, and particularly the method described in US. Pat. No. 2,815,150, the herein invention utilizing die construction which is an improvement over that shown in FIG. 22 of U.S. Pat. No. 2,815,150.

SUMMARY OF THE INVENTION This invention is, as stated, an improved automatic closure for semirigid, flexible squeezeable containers having the resiliently flexible characteristics of polyethylene or semirigid polyvinyl chloride and an improved method and means for fabricating the container. In the background patents and applications referred to, generally the containers shown have a neck portion with an automatic closure at the end of it, the side edges of the neck portion being closed, e.g., heat sealed together. Normally, this heat sealing has been done by way of sealing dies. It was discovered that due to the fact that the pressure of the heat-sealing die, when applied to the portions to be sealed, would depress or deform the material being heat sealed thereadjacent, leakage of the closure would sometimes occur. It was discovered that this deficiency can be overcome by the use of flat dies wherein adjacent to the heat-sealing elements or electrodes and flush therewith, there are provided dielectric inserts so that the closure portion of the container, when being heat sealed or the like, is subjected to clamping pressure exerted by opposed flat surfaces, thereby providing a uniform closure across the sealed area and eliminating the problem just described of hairline openings along the sealed edges of the neck inwardly adjacent said sealed edges. The sealed edges are carried to the tip of the outlet so that the out let is sharply defined with its sides flush and fully closed at the end.

Having been able to overcome this additional problem in the manner set forth, it was further discovered that an effective automatic closure could be created in a simple and effective way, particularly without the application of a separate stiffening or stretching member to the neck portion of the automatic closure as heretofore sometimes advantageously used with more rubbery or elastomeric materials such as rubber or plasticized vinyl, by the use of a stiffer, more self-supporting but nevertheless springy or resilient material of the nature of polyethylene.

Among other things, it was discovered that the problem of the formation of an undesired meniscus at the end of fluid material in a container when attempting to squeeze it out of a relatively narrow neck from a larger container body as described in the application referred to above (Ser. No. 535,11 1), could be met by way of appropriately tapering the neck of the container and heat scaling in accordance with the method described herein. Also, using the method of heat sealing described and the particular polyethylene materials referred to, or their like, a satisfactory automatic closure can be formed merely by incorporating an inherent transverse set or bow in the material at one or both sides of the neck of the container to hold the surfaces together at this point, except when manual pressure is applied to force contents out of the container; or optionally by preforming a lateral bow, curve or partial kink in or at the neck of the container.

Another object is to provide an improved automatic closure for squeezeable containers comprising a neck having tapered side edges sealed together to form an openable outlet having opposed lips either one or both of which is advantageously provided with an inherent reentrant curve, bow or set so that these lips normally oppose and preferably bear against each other provide a closure, except when manual or the like pressure is applied to the contained material.

Another object of the invention is to provide an improved method and improved dies, preferably heat sealing or super sonic-frequency dies or the like, for fabricating such self-sealing, flexible squeeze containers or bottles.

Another object is to provide improved dies for use in fabricating containers of the type referred to in the foregoing object, wherein sealing elements are provided with flush nonsealing inserts so that closely mating pressure is applied to the container during the sealing operation by way of flattening, preferably smooth, surfaces across the sealing area.

Further objects and additional advantages of the invention will become apparent from the following detailed description and annexed drawings, wherein:

FIGS. 1a, 1b, and 1c are views of a preferred form of automatic closure of the invention in perspective;

FIGS. 20, 2b, and 3 illustrate a clamp useable with the closure of FIGS. la, b, and c;

FIGS. 4a, 4b, and 5, and 6 illustrate a modified form of closure:

FIGS. 7a, 7b, 8, and 9 illustrate another modified form of closure;

FIGS. 10a, 10b, 11 and 12 illustrate another form of closure and method of fabricating it in perspective longitudinal sections, top unsealed and top sealed or completed views respectively;

FIGS. 13, 14, and I5 illustrate another form of automatic closure;

FIGS. 16 and 17 illustrate another form of closure, and double tube embodying the same;

FIG. 18 is a schematic view of a preferred form of equipment used in heat sealing in the inventions practice;

FIG. 19 is a schematic view of a continuous strip of tubular flexible material from which containers are formed by further processing;

FIG. 20 is an exploded view illustrating a preferred form of die and usage thereof;

FIG. 21 is a sectional view taken along the line 2l2I of FIG. 20;

FIG. 22 is a sectional view taken along the line 22-22 of FIG. 21;

FIG. 23 is a perspective view of a closure formed using the dies of FIGS. 18-22;

FIG. 24 is a perspective view of a modified form of die of the invention;

FIGS. 25 and 26 illustrate a simplified form of the invention wherein the automatic closure is formed simply by way of a kink in the neck, the material being suitable to accommodate this purpose.

FIGS. 27 and 28 show a modified and preferred form of the device of FIGS. 25 and 26.

FIGS. la, lb, and 10 show a preferred way to achieve positive closing pressure by inwardly bowed tension on the adjacent closure lips without changing the straight-lined slit appearance at the mouth of the tube as shown in FIG. 1b. Both lips are preformed with equal precurvatures as shown in FIG. la at 10 and 12 before sealing along the tapered edges 14 and 16 of tapered neck 9'. Such curvature or bow is readily accomplished during the blow molding or other such forming of the tube 9 itself. In this manner, it is also possible to place the adjacent lips under any desired closing tension by selection of materials of varying degrees of flexibility and rigidity and various wall thickness, and/or curvature. The manner of sealing along tapered edges is described in detail hereinafter.

If for example, the container is blow molded, the body of the container-including any desired bottom, presealed or notis formed in a conventional manner but including integral blanks for the lips 10 and 12, and an optional tearoff tab if desired. The blanks are each, however, as stated, advantageously formed with said inherent bow or curve, in equal but opposite directions. Thus, when the edges at 10 and 12 are compressed together and sealed in a flat plane, i.e., as viewed in FIG. 1b, they inherently maintain a closing bias on the outlet-due to their flexible resiliency. The resulting outlet can then be straight or it can have different degrees of curvature depending upon whether only one of the lips 10 or 12 are curved, or whether one is curved more than the other as aforesaid, as viewed end-on (as from the top, FIG. lb). In either event the contents l3 extrude through the outlet under sufficient digital pressure applied to the container body 9.

FIGS. 2a, 2b and 3 show a preferable flexible U-clip 20, useable with a container like that of FIGS. la b and c. It has dimples such as 22 and 24 cooperable with depressions such as 25 and 26 formed in the heat-sealed edges I4 and 16. When transporting the container as in a suitcase, it is desirable to have a locking seal or removable closure. The clip as shown slips over the end of the tube and retains the tube in tight sealing engagement, If desired it may be more or less permanently secured at one edge and provided with a detent closure at the other so as to permit a swinging opening movement and pivot on the other side which may be optionally releasably movable as well as shown in FIG. 2b. Such pivot may be provided simply by one of the detents or by a pivot stem or member.

In an alternative construction, as shown at 30, FIG. 4a, a container even one having a straight-line lip opening (as seen I in FIGS. 4b and 5), can be deliberately bowed laterally, i.e.,

out of its longitudinal axis in the manner of a complete or partial curve or kink (as described in connection with FIG. 25, 26 and 27) before sealing the edges of the closure. This can be accomplished as by means of correspondingly shaped dies or a preformed (molded-in) curve or partial kink in one or both lips to give any desired degree of tightness between said lips of the closure, in similar fashion to the curvature of the other figures but in an axis of curvature normal thereto. Thereby said resistance to flow by said lateral deflection or kink is put to use as a yieldable additional or separate closure force, if desired.

The container 30 is similarly formed having a tapered neck butof material of the nature of soft rubber or plasticized polyvinyl having less stiffness than polyethylene and its like.

Members 32 and 34 have a bow, i.e., set in them and are of any suitable resilient or springy plastic material and bonded to the end of the neck as shown to provide a configuration as in FIGS. 4b and 5. When bonded and operable as illustrated in FIG. 6, the closure opens in response to digital pressure.

FIGS. 7a, 7b, 8 and 9 show a modified form of the invention wherein members 32 and 34 are not used. The neck of container 40 is tapered as shown but may be shaped in any ornamental manner having a slight end flare of divergence 42 or such purpose as shown. When the tapered edges are heat sealed as shown a closure as illustrated in FIGS. 8 and 9 results.

In FIGS. 7a, 7b and 7c the outlet walls are flat and merely in touching contiguity with one another when viewed from the top (FIG. 7b) or in section (FIG. 8). The straight-walled, or flat, closure thus provided may not provide an adequate closing pressure for most liquid contents of a collapsible type of container or squeeze tube which is intended to be laid on its side; but in some uses, as for example in a standup bottle, it is adequate to provide a dustproof closure since the lips of the opening are in straight line, in closely contiguous or touching relationship from edge to edge, though unstressed. Thus, though preferably used for a standup-type container, it can be used as one which is intended to be laid on its side or hung upside down, if the contents of the tube are not under pressure and are relatively viscous and the lips flexible but sufficiently rigid. Otherwise positive closure pressure is required.

FlGSflOa, 10b, 11 and 112 of the drawings show a further modified form of the invention. In this embodiment the container is formed from a material such as polyethylene having said suitable degree of springiness or resiliency but having such a degree of stiffness that standup types of bottles or containers are customarily made from it. Such containers can be formed by any suitable method such as blow molding or the like, preferably with tapered neck 52 and tapered side edges 56 and 58, or integral side edges as in FIG. la wherein the edges 9', 9", l0 and 12 of the outlet define reentrant curves, or figure-eight shape in top view or cross section.

In this form of the invention the tapered side edges of the neck are optionally molded in an integral blank or in halves or blanks bonded together as aforesaid along their edges, but in either event the sides of the mouth define separated edges 56, 58 which when pressed together and sealed, form the outlet. Also a reentrant curve is formed on one or both sides of the neck. This curve may be impressed or formed as shown at 60, 62 on one or both sides of the neck as by a heated forming die or in the process of forming the blank. The bowed surface tapers downwardly and merges with the tube or container body 9. FIG. 10b is a longitudinal sectional view. FIG. 11 shows in top view the relative positions of the edges with the sides of the neck being brought together but prior to heat seal- The edges 56 and 58 are sealed together as in previous embodiments as designated at 66 and 58 (FIG. 12) whereupon the end of the neck appears as in FIG. 12 with the arcuate or bowed parts 60 and 62 held contiguously or flush against each other preferably in a more or less straight line as may be seen in said figure depending upon whether the relative curvature, stiffness and the like, of the lip blanks 60 and 62 are equal and opposite to one another.

The edges 56 and 58 respectively define openings which as shown are substantially V-shaped in FIGS. 10a, 10b, ll, 13 and 14; but as stated said blank-formed edge openings can be omitted and the container end initially preformed with in-' tegral outlet edges 9 and at least one inwardly curved side at 10 or 12 as shown, eg in FIG. la or one or both flat sides 42' or 42" as shown, eg in FIG. 7a, but as heretofore noted.

FIGS. 13, 14 and 15 show another form of the invention, which is like that of FIGS. 10a, 10b and 11 except that as may be seen in FIG. 13 the bows or curves 60 and70 are in the same direction but preferably with a lesser curvature in one of them to provide an opening of curved shape and preselected closing bias. FIG. I4 shows this construction with the edges 56 and 58 prior to heat sealing. FIG. 15 shows the neck after these edges have been sealed at 66 and 68. The closure is like that of the previous embodiment except that the opening or slit instead of being a straight line 72, as viewed in FIG. 12, is curved as shown in FIG. 15, forming in either case an end closure having a closing bias.

FIGS. 16 and 17 show a form of the invention adapted for containing two different miscible compounds which can be simultaneously squeezed from the container and then mixed, or, on the other hand, mixed within the container itself. The container in this form of the invention can be of any cross-sectlonal shape, but sufficiently long that it can be folded over and kinked" at 75 to separate the folded halves. Said halves are designated at and 82. The closure 84 is like that of any of the other embodiments with a tear strip 86 across the end, which may be torn off along the line 90. The folded portion 75 may be reduced in size and an openable or intermediate closure impressed thereon at either or both edges or centrally, but similarly formed as the other biased end closure, to fortify and increase the fluid-separation function of the kink fold itself which in this instance is a full kink fortified if needed by a simple C-shaped clamp 83 thereover and therealong which can be slid on for sealing or off for use.

The opposite ends of the full container are brought together and secured, as by the seal 86 to retain the fold formed kink 75 at or adjacent an advantageously located intermediate closure 72'. When the scored ends of the container are torn or otherwise cut apart and the tube like container unfolded, the contents can be squeezed from one tube half to the other and kneaded until mixed, then extruded through an end opening 72.

By way of illustration, FlGS. 18-22 of the drawings show flush heat-sealing dies which include sealing elements sandwiched between dielectric elements or placed adjacent to such elements so that the resulting surface which is intended to make the heat seal, and which may be as extensive as desired, is uniformly flat at least at and immediately adjacent this seal area so that any pinpoint or other undesired opening inwardly of the seam will not occur. It is necessary that in the tube outlet the confronting lips or sides be flush with one another so that the container, except when manually squeezed, is an effective closure.

It is desirable also to leave and cut out unsealed portions I around the neck, as in FIG. 19, to diminish the sealing load requirements on any electronic heat-sealing machine or equipment that is used. Thus, also in FIG. 1a, the excess material outwardly of the reentrant curves l0 and 12 is preferably cut away as at 12" when heating or otherwise sealing the edges 12 and 12".

in FIG. 19 the material from which a collapsible type of tube can be made is shown in a flattened condition, if desired, following heat sealing between the flush upper and lower heatsealing surfaces of the dies of the sealing machine.

The background art has dealt usually with an elastomeric material best illustrated by rubber, or plasticized vinyl, as stated. But in view of the limitations of rubber, from the standpoint of odor and other characteristics, vinyl and the like materials have in most uses been employed. These materials may still be employed in the heat-sealing process, with the referred to advantages of better closure, so far as the flush conditions of the dies and adjacent dielectric material shoulders are concerned. The stiffer but flexible polyethylenelike material which is essentially self-supporting is preferred when the outlet is unsupported, making a so-called standup bottle or container if desired.

FIGS. 25 and 26 show a closure having a narrowed neck 87, and tapered side parts 88, the edges being sealed as in previous embodiments. The material is selected so that a preformed or preset kink 89 is normally maintained to hold the container closed. Upon the application of digital pressure to the container the kink straightens out sufficiently to allow the contents to be discharged. Upon release of pressure the kink reappears, the material assuming its preformed state in which the closure retains the contents of the container.

The closure in FIGS. 27 and 28 is a preferred configuration having tapered side edges 90 and 91 and a similar kink 92, which as shown exaggeratedly, tends to unkink when pressure is applied to extrude the contents.

The nature of the container shown in FIGS. 1-17 will also be better understood from the method or technique of initial fabrication of the tube like orother collapsible container as illustrated in FlGS. 18-22, particularly as to the heat sealing which forms the openable closure.

FIG. 18 is a schematic view of the heat-sealing apparatus. lt embodies the platform or bed 100 which can form one of the supersonic, heat-sealing, or welding electrodes. Numeral 102 designates a typical heat-sealing or welding unit which may be of high frequency type which is connected electrically to an upper platen 103 which carries heatsealing die 134. The platen 103 is movable vertically by way of a hydraulic cylinder 105.

In a preferred technique, wherein collapsible containers are formed, either from plasticized vinyl or polyethylene or the like, the containers are made from initially a tubular material optionally wound on a reel or spool in a roll as designated at 106. This tubular material comes off the roll and passes over the platen or platform 100 under the control of any suitable, known, advancing device 107.

FIG. 19 is a view of a strip of the tubular material illustrating the areas which are heat sealed or to be heat sealed as the material passes through the heat-sealing equipment. Numeral 110 designates a single unit of the tubular material from which the containers are to be formed. As previously described, the

containers are preferably formed to have a tapered neck. A heat-sealed area across the mouth of the tube is provided at 112 and two diagonal heat-sealed strips 114 and 116 at the side edges. The units are cut along the line as designated at 120.

For use, the heat-sealed strip 112 can be torn or cut off, as disclosed in the above-cited art, leaving an openable closure at the line 112. The material exterior of the strips 114 and 116 can be trimmed off by suitably shaped dies and discarded.

FIGS. 20-22 illustrate the preferred forms of dies that are used to do the heat sealing.

Numeral designates a sheet of Micarta or a comparable material and laid over this is a sheet of release paper 131. The unit to be sealed is designated at 110 lying over the release paper or fabric 131. The upper platen 103 carries the die 134 which is made of suitable conductive material to do the heat sealing adjacent the inserts of dielectric material as designated at136, 138 and 140.

Thus, it may be seen that the sealing die 134 itself is configurated for a heat-sealed area as designated by the hatching in FIG. 19, and that adjacent to the die are the dielectric inserts 136, 138 and 140, so that the edges of the heat-sealed areas are evenly held and compressed together during heat sealing, eliminating the problem as described above of leaving pinholes or leakage points at the extremities of the heat-sealed areas 114 and 116 adjacent to the joined edges of the lips 140 and 142 (see FlG. 23).

It will be observed that when the unsealed areas 144 and 146 are cut away and the tear strip 112 is torn off, a container with a tapered neck is formed as shown in FIGS. 23 and 27, and it has an openable automatic closure at its end, as will be described hereinafter.

FIG. 24 of the drawings shows a modified form of upper die 150 which includes two additional sealing electrode strip members 152 and 154. This form of die is used when it is desired to fabricate the containers from simply strips of flat (or preformed) material that are laid over each other rather than from tubular material, so that it is necessary to heat seal along the edges of the container. Such heat scaling is accomplished by the strip electrodes 152 and 154, and of course a further electrode may be provided for sealing across the bottom of the container if a pillow-pak container is desired.

There may be included a still further intermediate strip electrode 156. This type of die is used to form a container having a seam or heat-sealed strip longitudinally down the center thereof, to form two separate compartments in the same container so that two different materials can be extruded from the container, simultaneously if desired.

It is to be noted that the above technique of flattening and compressing the outlet end of the container is the same for all types of plastic and other material used for making the containers, whether the container is ultimately in the form of a collapsible tube, or in the final shape of a standup bottle. Thus the use of a coil or tubular material is suitable for either polyethylene or vinyl tubes. It is preferable, however, that where the tube body is to be more cylindrical or more fully rounded in shape to preform the body thereof, without coiling or otherwise tending to store it in a flattened condition. Such preforming can be by blow molding or a like process.

For example, the main body of the tube, and even the lips can be preformed by blow-molding polyethylene (with or without an integral tear strip) all in one integral piece. Then the mouth is formed by compressing the end of the tube at the outlet, sealing the edges, and trimming the same as heretofore noted.

ln trimming the side edges of the outlet, sufficient of the breadth of the sealed area should be retained to insure its intended function of holding the lips of the outlet shut and closed. In this connection, as noted, the inherent curve in one or both of the lips is intended to bias the mouth of the tube into a tightly closed condition. Therefore, the opposed lips must not be formed with such respective radius of curvature as would cause the lips to remain apart, nor with such different cross-sectional lengths as to cause them to warp or wrinkle relative to one another when their edges have been sealed together. The axial length of the closed outlet portion is adjusted to the viscosity or capillary action of the particular contents and its tendency to creep over or wet the walls of the container and outlet.

From the foregoing those skilled in the art will understand the nature of the invention and the manner in which it achieves the objects and advantages set forth in the foregoing.

From the foregoing descriptions it will be apparent that the edge portions of the walls forming the outlet slit, when secured and sealed at the opposite edges, are yieldably and internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other edge portion to thereby provide yieldable sealing pressure.

The disclosure herein of representative forms of the invention is intended to be illustrative, the invention to be accorded the full scope of the claims appended hereto.

What is claimed is:

1. In combination with a resiliently flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting end edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said side edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions.

2. ln combination with a resiliently flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting end edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said side edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions, both said end edge portions being configured to tend to bow inwardly toward each other.

3. In combination with a resilient flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting end edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said said edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions, said side edges converging in a direction toward said end edge portions.

4. in combination with a resiliently flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting and edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said side edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions, said holding means comprising said side edges being fused and sealed together. 

1. In combination with a resiliently flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting end edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said side edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions.
 2. In combination with a resiliently flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting end edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said side edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions, both said end edge portions being configured to tend to bow inwardly toward each other.
 3. In combination with a resilient flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting end edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said said edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions, said side edges converging in a direction toward said end edge portions.
 4. In combination with a resiliently flexible container for fluids, said container having an outlet comprising opposed parallel and flexibly resilient wall portions having abutting and edge portions defining therebetween a closed-slit outlet, said wall portions having side edges extending, respectively, to opposite ends of said end edges, means holding said side edges in face-to-face abutting and sealed relationship, at least one of said end edge portions being yieldably internally stressed to tend to curve lengthwise of said slit to a shape bowing convexly toward the other end edge portion whereby to provide yieldable sealing pressure between said end edge portions, said holding means comprising said side edges being fused and sealed together. 